export type PromptParts = {
  pre: string
  prompt: string
  post: string
}

export function sanitizePromptPart(raw: unknown) {
  return String(raw || '').replace(/\r\n/g, '\n').replace(/\r/g, '')
}

export function composePromptParts(pre: string, prompt: string, post: string) {
  return [pre, prompt, post]
    .map(part => sanitizePromptPart(part).trim())
    .filter(Boolean)
    .join('\n\n')
}

export function applyPromptParts(parts: PromptParts, middle: string) {
  return composePromptParts(parts.pre, middle, parts.post)
}

function peelPromptWrappers(mid: string, pre: string, post: string) {
  let next = sanitizePromptPart(mid)
  if (pre && next.startsWith(pre)) next = next.slice(pre.length).replace(/^\n+/, '')
  if (post && next.endsWith(post)) next = next.slice(0, Math.max(0, next.length - post.length)).replace(/\n+$/, '')
  return next.trim()
}

export function restorePromptParts(saved: string, stored?: Partial<PromptParts> | null): PromptParts {
  const pre = sanitizePromptPart(stored?.pre ?? '').trim()
  const post = sanitizePromptPart(stored?.post ?? '').trim()
  return {
    pre,
    prompt: peelPromptWrappers(stored?.prompt ?? saved, pre, post),
    post
  }
}

export function formatPromptParts(
  stored?: { prompt?: string; promptPre?: string; promptPost?: string } | null,
  midOverride?: string
) {
  const pre = sanitizePromptPart(stored?.promptPre || '').trim()
  const post = sanitizePromptPart(stored?.promptPost || '').trim()
  const prompt = peelPromptWrappers(midOverride ?? stored?.prompt ?? '', pre, post)
  const blocks: string[] = []
  if (pre) blocks.push(`Pre-text\n${pre}`)
  if (prompt) blocks.push(pre || post ? `Prompt\n${prompt}` : prompt)
  if (post) blocks.push(`Post-text\n${post}`)
  return blocks.join('\n\n')
}